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  <title>Sort the entries with a user-defined comparison function and maintain key association</title>
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  <div id="layout-content"><div id="arrayobject.uasort" class="refentry">
 <div class="refnamediv">
  <h1 class="refname">ArrayObject::uasort</h1>
  <p class="verinfo">(PHP 5 &gt;= 5.2.0, PHP 7, PHP 8)</p><p class="refpurpose"><span class="refname">ArrayObject::uasort</span> &mdash; <span class="dc-title">Sort the entries with a user-defined comparison function and maintain key association</span></p>

 </div>
 <div class="refsect1 description" id="refsect1-arrayobject.uasort-description">
  <h3 class="title">说明</h3>
  <div class="methodsynopsis dc-description">
   <span class="modifier">public</span> <span class="methodname"><strong>ArrayObject::uasort</strong></span>(<span class="methodparam"><span class="type"><a href="language.types.callable.html" class="type callable">callable</a></span> <code class="parameter">$callback</code></span>): <span class="type">bool</span></div>

  <p class="para rdfs-comment">
   This function sorts the entries such that keys maintain their
   correlation with the entry that they are associated with, using a
   user-defined comparison function.
  </p>
  <p class="para">
   This is used mainly when sorting associative arrays where the actual
   element order is significant.
  </p>
  <blockquote class="note"><p><strong class="note">注意</strong>: 
 <p class="para">
  如果两个成员完全相同，那么它们将保持原来的顺序。
  在 PHP 8.0.0 之前，它们在排序数组中的相对顺序是未定义的。
 </p>
</p></blockquote>

 </div>


 <div class="refsect1 parameters" id="refsect1-arrayobject.uasort-parameters">
  <h3 class="title">参数</h3>
  <p class="para">
   <dl>
    
     <dt>
<code class="parameter">callback</code></dt>

     <dd>

      <p class="para">
       在第一个参数小于，等于或大于第二个参数时，该比较函数必须相应地返回一个小于，等于或大于 0 的整数。
      </p>
      <div class="methodsynopsis dc-description"><span class="methodname"><span class="replaceable">callback</span></span>(<span class="methodparam"><span class="type"><a href="language.types.declarations.html#language.types.declarations.mixed" class="type mixed">mixed</a></span> <code class="parameter">$a</code></span>, <span class="methodparam"><span class="type"><a href="language.types.declarations.html#language.types.declarations.mixed" class="type mixed">mixed</a></span> <code class="parameter">$b</code></span>): <span class="type">int</span></div>

     </dd>

    
   </dl>

  </p>
 </div>


 <div class="refsect1 returnvalues" id="refsect1-arrayobject.uasort-returnvalues">
  <h3 class="title">返回值</h3>
  <p class="para">
   总是返回 <strong><code>true</code></strong> 。
  </p>
 </div>


 <div class="refsect1 examples" id="refsect1-arrayobject.uasort-examples">
  <h3 class="title">范例</h3>
  <p class="para">
   <div class="example" id="example-3749">
    <p><strong>示例 #1 <span class="function"><strong>ArrayObject::uasort()</strong></span> example</strong></p>
    <div class="example-contents">
<div class="phpcode"><code><span style="color: #000000">
<span style="color: #0000BB">&lt;?php<br /></span><span style="color: #FF8000">//&nbsp;Comparison&nbsp;function<br /></span><span style="color: #007700">function&nbsp;</span><span style="color: #0000BB">cmp</span><span style="color: #007700">(</span><span style="color: #0000BB">$a</span><span style="color: #007700">,&nbsp;</span><span style="color: #0000BB">$b</span><span style="color: #007700">)&nbsp;{<br />&nbsp;&nbsp;&nbsp;&nbsp;if&nbsp;(</span><span style="color: #0000BB">$a&nbsp;</span><span style="color: #007700">==&nbsp;</span><span style="color: #0000BB">$b</span><span style="color: #007700">)&nbsp;{<br />&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;return&nbsp;</span><span style="color: #0000BB">0</span><span style="color: #007700">;<br />&nbsp;&nbsp;&nbsp;&nbsp;}<br />&nbsp;&nbsp;&nbsp;&nbsp;return&nbsp;(</span><span style="color: #0000BB">$a&nbsp;</span><span style="color: #007700">&lt;&nbsp;</span><span style="color: #0000BB">$b</span><span style="color: #007700">)&nbsp;?&nbsp;-</span><span style="color: #0000BB">1&nbsp;</span><span style="color: #007700">:&nbsp;</span><span style="color: #0000BB">1</span><span style="color: #007700">;<br />}<br /><br /></span><span style="color: #FF8000">//&nbsp;Array&nbsp;to&nbsp;be&nbsp;sorted<br /></span><span style="color: #0000BB">$array&nbsp;</span><span style="color: #007700">=&nbsp;array(</span><span style="color: #DD0000">'a'&nbsp;</span><span style="color: #007700">=&gt;&nbsp;</span><span style="color: #0000BB">4</span><span style="color: #007700">,&nbsp;</span><span style="color: #DD0000">'b'&nbsp;</span><span style="color: #007700">=&gt;&nbsp;</span><span style="color: #0000BB">8</span><span style="color: #007700">,&nbsp;</span><span style="color: #DD0000">'c'&nbsp;</span><span style="color: #007700">=&gt;&nbsp;-</span><span style="color: #0000BB">1</span><span style="color: #007700">,&nbsp;</span><span style="color: #DD0000">'d'&nbsp;</span><span style="color: #007700">=&gt;&nbsp;-</span><span style="color: #0000BB">9</span><span style="color: #007700">,&nbsp;</span><span style="color: #DD0000">'e'&nbsp;</span><span style="color: #007700">=&gt;&nbsp;</span><span style="color: #0000BB">2</span><span style="color: #007700">,&nbsp;</span><span style="color: #DD0000">'f'&nbsp;</span><span style="color: #007700">=&gt;&nbsp;</span><span style="color: #0000BB">5</span><span style="color: #007700">,&nbsp;</span><span style="color: #DD0000">'g'&nbsp;</span><span style="color: #007700">=&gt;&nbsp;</span><span style="color: #0000BB">3</span><span style="color: #007700">,&nbsp;</span><span style="color: #DD0000">'h'&nbsp;</span><span style="color: #007700">=&gt;&nbsp;-</span><span style="color: #0000BB">4</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">$arrayObject&nbsp;</span><span style="color: #007700">=&nbsp;new&nbsp;</span><span style="color: #0000BB">ArrayObject</span><span style="color: #007700">(</span><span style="color: #0000BB">$array</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">print_r</span><span style="color: #007700">(</span><span style="color: #0000BB">$arrayObject</span><span style="color: #007700">);<br /><br /></span><span style="color: #FF8000">//&nbsp;Sort&nbsp;and&nbsp;print&nbsp;the&nbsp;resulting&nbsp;array<br /></span><span style="color: #0000BB">$arrayObject</span><span style="color: #007700">-&gt;</span><span style="color: #0000BB">uasort</span><span style="color: #007700">(</span><span style="color: #DD0000">'cmp'</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">print_r</span><span style="color: #007700">(</span><span style="color: #0000BB">$arrayObject</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">?&gt;</span>
</span>
</code></div>
    </div>

    <div class="example-contents"><p>以上例程会输出：</p></div>
    <div class="example-contents screen">
<div class="cdata"><pre>
Array
(
    [a] =&gt; 4
    [b] =&gt; 8
    [c] =&gt; -1
    [d] =&gt; -9
    [e] =&gt; 2
    [f] =&gt; 5
    [g] =&gt; 3
    [h] =&gt; -4
)
Array
(
    [d] =&gt; -9
    [h] =&gt; -4
    [c] =&gt; -1
    [e] =&gt; 2
    [g] =&gt; 3
    [a] =&gt; 4
    [f] =&gt; 5
    [b] =&gt; 8
)
</pre></div>
    </div>
   </div>
  </p>
 </div>


 <div class="refsect1 seealso" id="refsect1-arrayobject.uasort-seealso">
  <h3 class="title">参见</h3>
  <p class="para">
   <ul class="simplelist">
    <li class="member"><span class="methodname"><a href="arrayobject.asort.html" class="methodname" rel="rdfs-seeAlso">ArrayObject::asort()</a> - Sort the entries by value</span></li>
    <li class="member"><span class="methodname"><a href="arrayobject.ksort.html" class="methodname" rel="rdfs-seeAlso">ArrayObject::ksort()</a> - Sort the entries by key</span></li>
    <li class="member"><span class="methodname"><a href="arrayobject.natsort.html" class="methodname" rel="rdfs-seeAlso">ArrayObject::natsort()</a> - Sort entries using a &quot;natural order&quot; algorithm</span></li>
    <li class="member"><span class="methodname"><a href="arrayobject.natcasesort.html" class="methodname" rel="rdfs-seeAlso">ArrayObject::natcasesort()</a> - Sort an array using a case insensitive &quot;natural order&quot; algorithm</span></li>
    <li class="member"><span class="methodname"><a href="arrayobject.uksort.html" class="methodname" rel="rdfs-seeAlso">ArrayObject::uksort()</a> - Sort the entries by keys using a user-defined comparison function</span></li>
    <li class="member"><span class="function"><a href="function.uasort.html" class="function" rel="rdfs-seeAlso">uasort()</a> - 使用用户自定义的比较函数，保持索引和值的对应关系，原地排序 array。</span></li>
   </ul>
  </p>
 </div>


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